1. Technical Field
The present application relates to a protection device for an electricity supply circuit for supplying a load with electricity, which immediately disconnects the circuit to protect the electricity supply circuit and the load when an overcurrent flows to the electricity supply circuit.
2. Related Art
For instance, a controller for controlling a load installed on a vehicle is equipped with a protection circuit that immediately disconnects a circuit when an overcurrent flows to the load. As a conventional example of such a protection circuit, there is known a protection circuit described in JP 2009-130944 A (PTL 1). In PTL 1, the quantities of heat generation and heat radiation of an electricity supply circuit (including a power line connecting a load with a power supply, and a power switch) are calculated on the basis of a current value flowing to the load and furthermore, the temperature of the electricity supply circuit is estimated upon measuring the ambient temperature. Then, if the estimated temperature reaches a predetermined threshold value, the controller disconnects the electricity supply circuit to protect a circuit connected to the load.